Syntheses and coordination chemistry of perfluoroaryl-1H-tetrazoles

Abstract

Attempts to prepare fluorinated 5-aryl-1H-tetrazoles by various methods were successful for (3,5-bis(trifluoromethyl)phenyl)tetrazole (BTFTH) and in part for 5-pentafluoropenyltetrazole (F5PhTetH) and 5-(tetrafluoro-4-pyridinyl)tetrazole (F4PyTetH). For BTFTH, several different methods gave satisfactory yields and purity. For the other compounds, the same methods allowed only the observation of the desired species in very small quantities in ill-defined reaction product mixtures with azidodefluorination being the dominant side reaction. Negative ionising MS proved to be superior to other MS methods showing clean elimination of mainly N2 and CF2 from the tetrazolate anions. From BTFTH, the Cu complex [(BTFT)2Cu(Py)2]n could be obtained and fully characterised, including crystal structure determination (for the complex and the ligand). Magnetic and EPR data for the polymeric [(BTFT)2Cu(Py)2]n suggest that the superexchange (SE) between the Cu2+ ions (S=½) is negligible. This can be understood by examining the crystal structure and the details of the possible SE path.